Food additives are substances that may be added to foods during processing in order to improve desirable chemical or physical characteristics and food quality. One of the most important forms of food additives are nutritional supplements. These typically comprise minerals and vitamins that are added to foods in order to restore nutritional values lost during food processing or to supplement the natural content of the food nutrients. The importance of the use of nutritional supplements to enhance the health and growth of farm animals has long been recognized in the field of animal husbandry.
It has also long been recognized that the production of nutritional supplements from various by-products of food rendering operations is highly desirable. Specifically, by establishing a commercial use for these by-products, the economic viability of the food rendering process is enhanced and otherwise difficult waste material handling is reduced or altogether avoided. This is a particularly important aspect for the poultry rendering industry where significant amounts of waste materials are produced. Accordingly, various methods have been developed for the utilization and processing of feathers and offal as a nutritional supplement for food products. Such processes are generally disclosed in, for example, U.S. Pat. No. 3,272,632 to Speer and U.S. Pat. No. 4,269,865 to Retrum.
One of the primary drawbacks in the prior art processing of waste products such as feathers and offal into nutritional supplements has been the heat degradation of various amino acids and proteins that effectively eliminates these materials as a source of nutrition. Accordingly, a need is identified for an improved method of processing waste products such as feathers and offal so as to avoid heat degradation of important amino acids and proteins and thereby provide a supplement with enhanced nutritional values.